docs: def get_etag(storage, path, prefixed_path):
      """
      Get etag of path from cache or S3 - in that order.
      """
      cache_key = get_cache_key(path)
      etag = cache.get(cache_key, False)
      if etag is False:
          etag = get_remote_etag(storage, prefixed_path)
          cache.set(cache_key, etag)
      return etag